It is easiest for the human eye to focus on distant objects. Using a computer  requires concentrating on work at close range, usually 18"-27" from the eyes. Close-range focusing may result in headaches, blurred vision and eye fatigue. 

You may relieve many computer-related vision problems by making one or more of the following changes: 

• Improve lighting in the work area 
  

• Alter the workstation 
  
• Change work habits 
  
• Prescription glasses designed for computer users 

Prescription glasses 

Intense demands on the eyes often cause visual problems. Even small amounts of the following conditions cause discomfort when using a computer: 

• Nearsightedness: when eyes see close objects more clearly than distant objects) 
  

• Astigmatism: when eyes see blurred or imperfect images) 
  
• Anisometropia: when eyeglass prescriptions are different for each eye. 
  
• Farsightedness: eyes see distant objects more clearly than close objects 
  
• Inefficient teaming of the two eyes: the two eyes don't coordinate well together. 

After an eye exam, your eye doctor may recommend computer glasses. These glasses are designed for the specific distance between the eyes and the screen.   Discuss your computer work with your optician when you purchase your glasses: 

• Tinted lenses can be helpful if your office uses fluorescent lighting. 
  

• Bifocals: some styles work better than others for computer use, ask your eye doctor or optician. Occasionally, task-specific, single-vision lenses are better. 

Lighting and glare control 

• Screen Brightness: Computer screen brightness should be three to four times greater than the overall lighting in the room. 
  

• You may need to remove or dim overhead lights, and use desk lamps with shades for other deskwork. 
  
• Natural light from windows should be controlled  with blinds or drapes. 
  
• Screen Placement: Reduce reflected glare on your computer screen by placing it so windows and other bright light sources are not directly behind or in front. 
  
• If you cannot solve glare problems by rearranging the furniture, try hoods that extend above the screen and glare shields that cover the screen.  However these devices may interfere with the screen's character resolution (the lightness or darkness of the type). 
  
• Tilting the screen also may reduce glare. 
  
• Contrast: Adjust the contrast (the lightness or darkness of the screen) to a comfortable level using the knobs on the terminal. 

Workstation suggestions

• Monitor Position: about 20 degrees below eye level. 
  

• Reference Material Placement: Place reference material as close to the monitor as possible. Copy holders are helpful in holding the material in place. By arranging the copy next to the screen, you reduce the need for excessive eye and head movements. 

Body Posture: 

• Your monitor should be positioned 24"-28" from your eyes, directly in front of you, with the top of the screen at eye level. 
  

• The center of the screen should be about 20 degrees below eye level.
  
• Your monitor height should be adjustable.
  
• Reference material placed next to screen.
  
• Wrists in a straight or "neutral" position.
  
• Upper arm and forearm create 90 degree angle.
  
• Your chair height should be adjustable with good lower back support. 
  
• Elbow, hip, and knee joints should be as close to 90" as possible. 
  
• Feet should be flat on the floor or on a footrest. 

Work habits 

• Take regular breaks from your computer, such as 2-3 minutes each half-hour and 10-15 minutes every 2 hours. 
  

• Look out a window or at an object at least 20 feet away to relax the eyes. Distance Focusing: Regularly focus on distance objects.  Maintaining a close focus on the computer monitor can create a focusing spasm. 
  
• Do simple stretching exercises to relax the whole body.